1. Field of the Invention
This application is directed to ashless dispersants derived from Mannich Reaction of hydrocarbyl succinimides and saccharin.
2. Description of Related Art
Alkyl- or alkenylsuccinimides are well known in the art as ashless dispersants for lubricants and fuels. Their principal function in such applications is to prevent the deleterious sludge accumulation on engine parts. Because of today's hotter running engines, the performance properties of ashless dispersants are being optimized to cope with the increased sludge formation resulting from increased thermal and oxidative degradation of lubricant formulations.
This invention is directed to novel multifunctional ashless dispersants derived from Mannich reaction of hydrocarbyl succinimides, saccharin and carbonyl compounds. See U.S. Pat. No. 5,186,850. See also U.S. Pat. Nos. 5,130,036 and 4,857,214 which disclose ashless dispersants comprising a hydrocarbyl succinimide, a mixed ester/amide, hydroxyesters and the Mannich condensation products of hydrocarbyl-substituted phenols, formaldehyde and polyamines.
Saccharin, of course has found widespread use in the sweetening art. However, U.S. Pat. No. 4,689,218 discloses an effervescent composition with analgesic activity having an artificial sweetener such as saccharin, a binder and a lubricant such as polyethylene glycol.
Today's hotter running engines require more highly dispersant oil formulas to minimize the increased sludge formation and deposits on engine parts. Consequently, in addition to increased dispersant activity, the ashless dispersants must be compatible with, and if possible, provide additional performance protection to these oil compositions. By incorporating antiwear and antioxidant functionalities into existing succinimide ashless dispersants, the chemistry of this invention has made it possible to optimize their effectiveness and also expand their application. This is especially significant in view of current and projected industry-wide efforts to minimize the concentration of, or replace, the zinc dithiophosphates (ZnDTP) which have, historically, provided the multifunctional antiwear and antioxidant protection to a large variety of lubricant formulations.
The synergistic combination of the succinimide and the sulfur-and nitrogen-containing heterocyclic saccharin functionalities in the products of this invention provides ashless dispersants with additional multifunctional antioxidant, antiwear and potential metal passivator properties for lubricant compositions. To the best of our knowledge, the syntheses and applications of this class of compounds have not been disclosed elsewhere and are, therefore, novel.